Morning Kay. race
Welcome to the Forum
Most of my experience with 5 series has been with my brother in-law cars he is on number 5.
All his cars have been owned from new and covered 150k+ before trade in for the next. he has it serviced by BMW to their schedule (mainly to ensure they accept it as a trade in) but in between we carry out additional oil changes and take care of any niggles. There have been a few well publicised faults over the years which BMW have mostly fixed.
Your car a 50k with a full history should be fine, my personal feelings are extended service intervals do not help a cars life which is why we carry out interim service's on his cars as I do on my own.
Check its history and make sure all recalls have been attended to make sure everything works as it should. Then drive it and enjoy it
Dave